Restrictions have eased and lockdowns have lifted, but Adelaide epidemiologist Adrian Esterman grows uneasy at talk of a post-COVID world, especially at a time of rising reinfection.
While the term is often only used loosely, the University of South Australia professor believes its prevalence in daily conversation reflects a creeping casualness in public attitudes.
"In South Australia we're getting 2,500 cases a day, we're getting several deaths a day, we've got all these thousands of people reinfected, [and] hospitalisations are sitting over 200," Professor Esterman said.
"We simply don't know yet."
The number of COVID cases recorded nationally since the start of the pandemic has reached 8 million.
But the ongoing focus on infection is being supplemented by a growing focus on reinfection — even if people who have twice caught COVID comprise a very small fraction of the total.
In South Australia, where authorities have warned of another COVID wave linked to the BA.5 subvariant, SA Health figures indicate the number of reinfections has reached about 3,000, out of more than half a million total cases.
Reported reinfection cases in SA to date |
Proportion of all SA recorded cases |
|
|---|---|---|
June 6 |
2,033 |
0.38 per cent |
June 13 |
2,304 |
0.42 per cent |
June 20 |
2,627 |
0.46 per cent |
June 27 |
2,990 |
0.51 per cent |
In proportional terms, however, reinfections are on the rise.
"I keep hearing tales of people catching it within three or four weeks of recovering," Professor Esterman said.
"We really do not have a good handle on reinfections. Does that matter?"
Answering that question is difficult. Generalising about reinfection is challenging because of the number of variables, and variants, involved.
"It depends how different your original infection was from the next one that's around," Professor Esterman said.
While it has not yet been peer-reviewed, recent US research suggests the chance of negative health impacts increases with each infection.
Professor Esterman added there was another "burning issue" where reinfection was concerned.
"Does it lead to an increased or a decreased chance of getting long COVID?" he said.
'That's not the choice'
Deakin University epidemiology chair Catherine Bennett is also interested in reinfection's ramifications.
Our current understanding of reinfection might seem at least partly anecdotal, and Professor Bennett said more research was needed to ensure it was made more analytical.
"Some people have experienced more severe infections on subsequent rounds. And that could be true for BA.5 anyway, because BA.5 has a better ability to bind to proteins in our lung lining," she said.
"We're also seeing within Omicron, particularly with these waves of subvariants, that there is an ongoing risk of continual reinfection, so you might have a short period where your immune system's boosted but then you get infected again.
Like Professor Esterman, Australian National University infectious diseases expert Peter Collignon suspects reinfection leads to "much milder disease than the first episode you had", but said there were exceptions.
"All the available evidence is you're less likely to end up in hospital or die," Professor Collignon said.
"Does that mean you're completely protected if you've had a first infection? No, it doesn't.
"Some people, with their second infection, it's worse than the first, and it seems to be particularly people who get it in the first two or three months [after the first infection]."
Professor Collignon said our understanding of reinfection remains incomplete at best.
"There's a lot of questions we need answers to," he said.
"There may be something we still don't understand about immunity — that if you either don't get rid of the virus, or you get it back before your body's had time to really learn properly, you may get worse symptoms, particularly in the first month or two."
But what the experts are certain of is vaccination's role in reducing severe illness and they recommend steps to "avoid infection if you can".
"It's not whether you have an infection now or later. It's whether you have one infection or many infections."
